Recent clinical success with right atrial to pulmonary artery bypass conduits for tricuspid atresia stimulates interesting questions regarding the physiology of blood flow through the conduit. Since the right atrium becomes the sole pumping chamber on the right side of the heart, it would seem that normal sinus rhythm would be required for optimal flow through the conduit. However, there have been reports of patients adequately tolerating nodal rhythm as well as supraventricular arrhythmias. Thus, the importance of sinus rhythm for hemodynamic success is not clearly established. Furthermore, the necessity of including a valve in the conduit has been questioned.